1. Field of the Invention
The present invention relates to a stopper for a container with a neck, of the kind comprising a body which may be fixed and sealed to the container's neck and wherein at least a duct is formed for emptying the container and a shutoff valve for closing up said duct. The present invention also relates to a container provided with such a stopper.
2. Description of the Prior Art
Such stoppers of the aforementioned kind are already known. Such a stopper is for example described in French Patent FR-2 687 130. This known stopper comprises at least four separate parts, i.e. a body, a cage, a ball and a spiral spring, which have to be assembled together to form the stopper. As a result, manufacturing of the stopper is relatively complicated.
French Patent FR-2 616 756 further describes a stopping device for a flask, which only comprises two parts, both formed as a cap. One of these two parts or internal cap, in use, just caps the flask's neck and is sealed thereto, whereas the other unit or external cap caps the internal cap and may rotate relatively to the latter around an axis coinciding with the axis of the flask's neck. A chamber is provided between the upper walls of both caps. The upper wall of the external cap is formed as a thin wall so as to form an elastic diaphragm, and it bulges towards the upper wall of the internal cap. At its center, the elastic diaphragm includes an orifice which engages with a boss formed at the center of the upper side of the internal cap, such as to seal the central orifice of the elastic diaphragm. On another side, the upper wall of the internal cap includes two eccentric orifices, which are formed on both sides of the central boss and which engage with two bosses formed at a matching location on the lower side of the elastic diaphragm, so as to seal these two orifices. By rotating the external cap relatively to the internal cap, a slight elastic distortion of the diaphragm occurs and both bosses thereof clear both orifices of the upper wall of the internal cap, thereby the inside of the flask communicates with the chamber formed between the upper walls of both caps. Now, if the pressure inside the flask is increased, for example by manually applying pressure on the distortable walls thereof, distortion of the elastic diaphragm is increased and the central orifice of the diaphragm moves away from the central boss of the internal cap, thereby the aforementioned chamber communicates with the outside of the flask, so that the fluid substance contained therein can flow towards the outside of the flask. Although the stopping device of French Patent FR-2 616 756 includes a smaller number of parts and that as a result, its manufacturing is simpler than that of the stopper of French Patent FR-2 687 130, it has nevertheless certain drawbacks. Especially, when first using the flask, the elastic diaphragm distorts under the effect of an increase in pressure inside the flask and the substance which penetrates into the chamber between the upper walls of both caps may flow not only towards the outside through the central orifice of the elastic diaphragm, but also into the ring-shaped space between the cylindrical skirts of both caps. It is very difficult to extract any substance therefrom which has penetrated into this ring-shaped space, particularly when it is a sticky or thick substance. As a result, this substance will stagnate between the skirts of both caps throughout the period of use of the flask. Not only is this not hygienic, notably for food substances, but also the substance included between the skirts of both caps may cause both caps to stick to one another, thus making a subsequent opening of the stopper device very difficult, if not impossible.
Furthermore, it may happen that under the action of strong pressure inside the flask, the elastic diaphragm distorts to the point that its curvature is reversed, i.e. from concave to convex, and that it remains in the convex state when pressure is released, so that the stopping device stays open. As a result, air can penetrate into the inside the flask. This can impair good preservation or sterility of the substance contained in the flask.
In the case considered above, the stopping device must then be sealed once more by applying pressure on the elastic diaphragm so as to bring it back to its concave state. If this operation is carried out with a finger, this is bad for hygiene or this may be harmful if the flask contains a substance, for example a toxic or corrosive substance, which must not be touched with fingers. Finally, with the stopping device of French Patent FR-2 616 756, as with the stopper of French Patent FR-2 687 130, it is impossible to fill the flask without having removed beforehand the stopper or stopping device. Indeed, the shutoff valve included in the stopper of French Patent FR-2 687 130, like the elastic diaphragm of the stopping device of French Patent FR-2 616 756 only allows flow from the inside to the outside of the flask. Accordingly, if particular precautions or restricting steps are not adopted upon filling the flask, the filling substance is in contact with air from the environment during the whole filling period and until the stopper or stopping device is put back into place in the flask's neck.